What is the function of the Internet?

Basic services and functions of the Internet:

Service www

The World Wide Web (WWW) is a global information resource network that integrates multimedia information such as text, sound, image and video, and is an important part of the Internet. Browser is a bridge for users to access WWW and a window for users to obtain WWW information. Through the browser, users can roam in the vast ocean of Internet, search and browse all the information they are interested in.

The webpage files of WWW are written in Hypertext Markup Language (HTML) and run under the support of Hypertext Transfer Protocol (HTTP). Hypertext contains not only text information, but also multimedia information such as graphics, sounds, images and videos (so hypertext is also called hypermedia). More importantly, hypertext means linking to other hypertext, which is called hyperlink. Using hypertext, users can easily link from one webpage to other webpages with related content, without worrying about where these webpages are scattered on the host.

HTML is not a general programming language. It embeds special tags in the document, describes the semantics of a paragraph of text, produces multimedia effects after interpretation, and provides hyperlinks to the text.

WWW browser is a client program whose main function is to enable users to access various resources on the Internet. Commonly used browsers are Microsoft IE and Netvigator/Communicator. SUN also developed a browser HotJava written in Java. Java is a new dynamic interpretation language, which is independent of various operating systems and platforms. Java animates browsers and provides real-time interactive functions for connected users. Common browsers support Java.

Email service

E-mail is the most widely used service on Internet. As long as users can connect to the Internet and have programs and personal email addresses that can send and receive emails, they can exchange emails with all users on the Internet conveniently, quickly and economically. They can exchange emails between two users, send the same email to multiple users, or forward the received email to other users. Besides text, e-mail can also contain various computer files, such as sounds, images and applications. In addition, users can subscribe to e-magazines, get the required documents, participate in related announcements and discussion groups, and even browse WWW resources online.

Sending and receiving e-mails must be supported by corresponding software. Commonly used e-mail sending and receiving software include Exchange and Outlook Express, which provide functions of receiving, editing, sending and managing e-mail. Most Internet browsers also include the function of sending and receiving e-mail, such as Internet Explorer and Navigator/Communicator.

The protocols used by the mail server include SMTP (Simple Mail Transfer Protocol), MIME (Multipurpose Internet Mail Extension) and POP (post office protocol) in post office protocol. POP service needs to be provided by mail server, and users must obtain an account on the mail server to use the service. The commonly used POP protocol is version 3, so it is also called POP3 protocol.

Newsgroup network newsgroup service

Newsgroup is a collection of discussion groups organized by many like-minded users. It is also commonly called Global Bulletin Board System (BBS). Newsgroups are used to publish announcements, news, comments and various articles for online users to use and discuss. The discussion content is organized according to different topics, and each category is a topic group, which can be divided into more sub-topics.

Every news in a newsgroup is guided by different types of tags, and each newsgroup revolves around a theme, such as comp. (Computer content), news. (news and information usenet itself), suggestions. Sports, arts and entertainment activities. (science branch), soc. (social problems), talk about. (discussion and communication) and misc (others.

Users can not only choose to participate in the thematic groups they are interested in, but also form new thematic groups themselves. As long as someone participates, the thematic group will last forever; If no one participates for a period of time, this topic group will be deleted automatically.

file transfer protocol server

Text transmission service, also known as FTP service, is one of the earliest service functions provided in the Internet and is still widely used.

FTP (File Transfer Protocol) protocol is the basis of file transfer on the Internet, and FTP is a service based on this protocol. FTP file transfer service allows users on the Internet to transfer files from one computer to another. Almost all types of files, including text files, binary executable files, sound files, image files and data compressed files, can be transmitted through FTP.

FTP is actually a set of file transfer service software, which uses simple get or put commands to download or upload files, just like executing file copy commands on the Internet. Most FTP server hosts use Unix operating system, but ordinary users can also use FTP conveniently through Windows95 or Windows 98.

The biggest feature of FTP is that users can use many anonymous FTP servers on the Internet. The so-called anonymous server refers to a system that can enter without a special user name and password. When users connect to an anonymous FTP server, they can log in with "anonymous" as their user name and their email address as their password. After logging in successfully, users can download files from anonymous servers. The standard directory of anonymous server is pub, and users can usually access files in all subdirectories under this directory. Considering security issues, most anonymous servers do not allow users to upload files.

Remote login service

Remote login service, also called Telnet service, is one of the earliest service functions provided on the Internet, and many people still use this service function.

Telnet is a protocol of Internet remote login service, which defines the way for remote login users to interact with the server. Telnet allows users to log on to a remote time-sharing system on a networked computer, and then use the remote system as if it were their own computer.

To use the remote login service, you must start the client application on the local computer, specify the name of the remote computer, and establish a connection with it through the Internet. Once the connection is successful, the local computer can directly access the resources of the remote computer system like an ordinary terminal. Remote login software allows users to interact directly with remote computers. Through keyboard or mouse operation, the client application sends relevant information to the remote computer, and then the server returns the output result to the user. After the user logs off the remote login, the user's keyboard and display control rights will be returned to the local computer. Ordinary users can log in remotely through the Telnet client program of Windows.

Bulletin board system service

BBS (Bulletin Board Service) is an electronic information service system on the Internet. It is a very popular way of communication between individuals and groups. Nowadays, BBS has formed a unique network culture. Netizens can freely express their thoughts and opinions through BBS. BBS is actually a kind of website. From a technical point of view, the bulletin board system is actually a public information storage area set up on the network computers in a distributed information processing system. Any legal user can access the information in this storage area through the Internet or local area network. Early BBS can only provide plain text forum services, and BBS can also provide e-mail, FTP, newsgroups and other services. BBS is divided into several columns according to different themes, and the division of columns is established according to the needs and preferences of most BBS users. The right to use BBS is divided into browsing, posting, sending emails, sending files and chatting. Almost any Internet user has the right to browse freely, and only officially registered users can enjoy other services. The biggest difference between BBS and the Internet is that, as its name describes, it is a "bulletin board", that is, most of the emails running on BBS websites are official letters. Therefore, users will face almost all the information on the website. The Internet in China first developed from universities and scientific research institutions. Universities usually set up campus networks, so students and teachers naturally become the biggest users of BBS.

Other internet services

1, VoIP

VoIP is the latest technology on the Internet, which makes people's fantasy of calling any ordinary phone in the world through PC come true. As a pioneer of communication and Internet service, the VoIP developed by IDT Company in the United States is in a leading position in global network communication. Its network telephone system enables any multimedia computer user with a sound card on the Internet to make an international long-distance call, and the signal is transmitted to the server of IDT Company in the United States through the Internet, which will be automatically transferred to any ordinary telephone of the called party, and the other party's telephone will ring, so that both parties can conduct real-time full-duplex communication. When using this system to make an international call, it can save up to 95% of the cost compared with the traditional international long-distance call, because the signal is transmitted to the server in the United States through the Internet and then to the called phone, instead of the traditional telecommunication transmission, thus achieving the purpose of reducing the cost. With VoIP, you can call any ordinary phone from PC, which changes the technical limitations of VoIP from PC to PC.

2、IRC

IRC (Internet Relay Chat) is a network instant chat system. Its biggest advantage is that it is extremely fast, users can hardly feel the stagnation of information when sending information, and support online file transfer and secure private chat. Compared with BBS, it has a more intuitive and friendly interface. The development of IRC is amazing, and more and more people all over the world are involved in the secondary development of IRC and the production of client software. There are also several IRC chat rooms in China. IRC chat will replace other chat methods and enter the life of every network user.

IRC uses very rich software, such as PERCH, SCHAT, etc. MIRC, the most popular IRC client software produced by mIRC Company in Britain, became popular all over the world as soon as it was launched. Through this software, as long as everyone uses the same address and enters the same server (even without entering the server), information can be transmitted to one or more other users who are online at the same time. This is a very practical and powerful real-time chat software.

3、ICQ

ICQ is the abbreviation of English I seek you, which is often called "Web Pager" and is a free network software. The main function is to send information or communicate with users who have also installed ICQ on the Internet. It is an instant messaging software developed by Israel Strange Company in 1996, which can send short messages, voice messages, chats and files, so that users can check the networking status of their friends. But also has a powerful "integration" function, which can integrate pagers, mobile phones, emails and other communication methods.

Step 4 contact and chat

5. Shopping online

6. Network video

7. Weibo

8. Online community